All three projects in the Center require mutant mice derived at UCLA. The Mouse Genetics Core will reside in a SPF facility at UCLA and will facilitate the back-cross, mating and dissemination of the mutant mice required by all three Projects in the center. The facility will maintain the lines, genotype them and send them when needed to the participating laboratories. An important role for the facility will be to transfer mutations into stable genetic backgrounds that could then be retested and sent to the laboratories in the Center. Some of the mice that will be tested in the genetic screen proposed in Project 1 are not in stable, balanced genetic backgrounds. The Mouse Genetics Core will use speed congenics and other techniques to transfer selected mutations into stable and defined genetic backgrounds. The facility will also be responsible for the distribution of mice with conditional mutations of genes identified in the plasticity screens proposed. The integration of studies in the Center is completely dependent on the uniformity of the genetic background of the mice tested. Since phenotypes, including brain phenotypes, are sensitive to genetic background, it would be impossible to integrate findings from different laboratories in the Center, if each laboratory used mice with varying genetic background. Thus, providing mice of uniform genetic background is a crucial and key function of the Mouse Genetics Core.